Methods and nodes in a radio communication system with efficient control channel use

ABSTRACT

The present invention generally relates to radio communication systems, relay nodes, controller nodes, user equipment (user terminals), software and methods for said systems and nodes. In one embodiment, a method for operating a control node for a wireless communication system is provided. The method comprises the steps: creating a data frame comprising an early part and a later part, wherein the early part comprises first control data for controlling a receiving node; checking whether second control data are to be put into the later part; scheduling payload data for the receiving node into the later part if second control data are not to be put into the later part; and transmitting the date frame to the receiving node.

This application claims the benefit of U.S. provisional patentapplication No. 61/330,580 filed on May 3, 2010, the disclosure of whichis fully incorporated herein by reference.

TECHNICAL FIELD

The present invention generally relates to radio communication systems,relay nodes, controller nodes, user equipment (user terminals), softwareand methods for said systems and nodes and, more particularly, tomechanisms and techniques for handling communications in radiocommunication systems which include relays. In particular, a design of aRelay-Physical Downlink Shared Channel (R-PQSCH) is presented.

BACKGROUND

The background is described with respect to LTE (Long Term Evolution).The skilled person will however realize that the principles of theinvention may be applied in other radio communication systems,particularly in communication systems that rely on scheduled datatransmissions.

The downlink transmission of the LTE (Long Term Evolution), or E-UTRANradio access, is based on Orthogonal Frequency Division Multiplex(OFDM). The basic LTE downlink physical resource can thus be seen as atime-frequency grid as illustrated in FIG. 1, where each resourceelement (RE) corresponds to one OFDM subcarrier during one OFDM symbolinterval. The dark shadowed resource elements form a resource block.

In the time domain, transmissions in LTE are structured into frames andsubframes. Each frame of length T_(f)=10 ms consists of tenequally-sized subframes of length T_(subframe)=1 ms. Each subframe, inturn, consists of two equally-sized slots of length T_(slot)=0.5 ms.

Resource blocks (RBs) are also defined in LTE, where each RB consists of12 contiguous subcarriers during one slot. The subcarrier spacing is setto Δf=15 kHz. In addition, a reduced subcarrier spacing of 7.5 kHz isdefined targeting multicast broadcast transmissions in single-frequencynetworks.

Generally a resource element may be defined by certain ranges in anycombination of the transmission resource, which are essentially time,frequency, code and space, depending on the actual transmission systemunder consideration.

The LTE time domain structure, in which one radio frame is divided intothe 10 subframes #0 to #9 and each subframe is divided into a first anda second slot, wherein the first slot is an early part and the secondslot is a later part of each subframe, is depicted in FIG. 2.

In LTE data transmissions to/from a user equipment (UE) are under strictcontrol of the scheduler located in the eNB. Control signaling is sentfrom the scheduler to the UE to inform the UE about the schedulingdecisions. This control signaling, consisting of one or several. PDCGHs(Physical Downlink Control Channels) as well as other control channels,is transmitted at the beginning of each subframe in LTE, using 1-3 OFDMsymbols out of the 14 available in a subframe (for normal CP andbandwidths larger than 1.8 MHz, for other configurations the numbers maybe different).

Downlink scheduling assignments, used to indicate to a UE that it shouldreceive data from the eNB occur in the same subframe as the data itself.Uplink scheduling grants, used to inform the UE that it should transmitin the uplink occur a couple of subframes prior to the actual uplinktransmission.

Generally, control data may comprise at least one of a downlinkassignment and an uplink grant.

Among other information necessary for the data transmission, thescheduling assignments (and grants) contain information about thefrequency-domain location of the resource blocks used for datatransmission in the first slot. The frequency-domain location of the RBsin the second slot is derived from the location in the first slot, e.g.by using the same frequency location in both slots. Thus, schedulingassignments/grants operate on pairs of resource block in the timedomain. An example hereof is shown in FIG. 3.

In FIG. 3, the slopingly hatched parts in each resource block 0 to 9contains control data, whereas the horizontally hatched parts containpayload data. The subframe is divided into a first slot and a secondslot. The control data is part of the first slot.

Relaying is considered for LTE-Advanced as a tool to improve e.g. thecoverage of high data rates, group mobility, temporary networkdeployment, the cell-edge throughput and/or to provide coverage in newareas. The relay node (RN) is wirelessly connected to the radio-accessnetwork, for example via a donor cell controlled by a donor eNodeB(eNB). The RN transmits data to/from UEs controlled by the RN and mayuse the same air interface as an eNB, i.e. from a UE perspective thereis rib difference between cells controlled by a RN and an eNB.

Due to the relay transmitter causing interference to its own receiver,simultaneous eNB-to-RN and RN-to-UE transmissions on the same frequencyresource may not be feasible unless sufficient isolation of the outgoingand incoming signals is provided e.g. by means of specific, wellseparated and well isolated antenna structures. Similarly, at the relayit may not be possible to receive UE transmissions simultaneously withthe relay transmitting to the eNB.

One possibility to handle the interference problem is to operate therelay such that the relay is not transmitting to terminals when it issupposed to receive data from a control node, e.g. the donor eNodeB,i.e. to create “gaps” in the relay-to-UE transmission. These “gaps”during which terminals (including 3GPP Rel-8 terminals) are not supposedto expect any relay transmission can be created by configuring MBSFNsubframes as exemplified in FIG. 4. MBSFN subframes contain a smallcontrol signaling part at the beginning, followed by a silent periodwhere the UEs do not expect any transmissions from the RN.

During the time period or frame or subframe, in which the UE does notexpect data and/or in which the RN does not transmit data to the UEs,the RN can receive data, for example control data of the eNB.

RN-to-eNB transmissions can be facilitated through scheduling by notallowing any terminal-to-relay transmissions in some subframes.

One aim of the invention is to provide methods for efficientlytransferring control data and payload data in a network scenariocomprising a control node (donor eNB), a relay node and possibly severalUEs. Therein the above interference problem associated with the use ofrelay nodes shall be solved.

The invention is particularly relevant for LTE based systems. Downlinkcontrol signaling is discussed in Section 16.2.4, pages 333 to 336, ofthe book entitled 3G Evolution: HSPA and LTE for Mobile Broadband, firstedition 2007 by Dahlmann, Parkvall Skoeld and Beming. It is also pointedto the standards 3GPP LTE Rel-10 and to the technical reports 3GPP TR36.814 and 36.912. Multiplexing a Relay Physical Downlink ControlChannel (R-PDCC) in the downlink subframe from the donor eNB isdiscussed in U.S. 61/308,385. The cited references/documents areincorporated by reference herewith.

SUMMARY

The invention focuses mainly on the communication between a control node(e.g. a eNB) and a relay node (RN). The invention focuses also on thecommunication between a control node and a UE. FIG. 7 shows a radiocommunication system comprising a control node (eNB) with a scheduler, arelay node (RN) and a first (UE 1) and a second user equipment (UE 2).Each of the control node, the relay node and the first and second userequipment comprises a transmitter and a receiver. The control node, therelay node and the user equipment are connected via a wirelessinterface. The arrows indicate possible uplink and downlinkcommunications. The invention focuses on the communication between thecontrol node and the relay node. The invention can also be applied to acommunication between a control node, and a UE. The direction from thecontrol node to the relay node is considered as downlink, the directionfrom the relay node to the control node is considered as uplink.

The invention relates to a method for operating a control node for awireless communication system comprising the steps: creating a dataframe comprising an early part and a later part, wherein the early partcomprises first control data for controlling a receiving node; checkingwhether second control data are to be put into the later part;

scheduling payload data for the receiving node into the later part ifsecond control data are not to be put into the later part; andtransmitting the data frame to the receiving node.

Advantageously the receiving node is a relay node. The receiving nodemay also be a UE.

The method may further comprise putting second control data into thelater part. The first control data may comprise a downlink assignment,the second control data may comprise an uplink grant.

Advantageously, the first control data indicates the resource on whichthe first control data are transmitted if payload data are to betransmitted in the second part.

The payload data may be data for the receiving node only.

The control node can be an eNodeB and also a Pico-eNodeB.

The first control data may comprise an indication on resources on whichpayload data are transmitted. It is advantageous that the resource onwhich the first control data are transmitted is indicated, if payloaddata is transmitted in the later part. The resource may, for example, bea frequency band or a set of subcarriers.

The early part and the later part may be transmitted with differenttransmission methods. The later part may advantageously be transmittedwith a higher throughput than the early part. The early part and thelater part may also be transmitted with an identical transmissionmethod. The first part and the second part may have a flexible border.The border may be put in the middle of the data frame. The data framemay also be regarded as a subframe.

The invention also relates to a control node for a wirelesscommunication system comprising: a controller for creating a data framecomprising an early part and a later part, wherein the early partcomprises first control data for controlling a relay node; a checkingentity for checking whether second control data are to be put into thelater part;

a scheduler for scheduling payload data for the relay node into thelater part if second control data are not to be put into the later part;and a transmitter for transmitting the data frame to the relay node.

The control node may further comprise a putting entity for puttingsecond control data into the later part.

The invention relates also to a method for operating a receiving nodefor a wireless communication system comprising the steps: receiving adata frame from a control node, wherein the data frame comprises anearly part and a later part, wherein the early part comprises firstcontrol data for controlling the receiving node, detecting whether thelater part contains second control data or payload data; and processingthe later part in dependence of the detection.

Advantageously the receiving node is as relay node. The receiving nodemay also be a UE.

The first control data may indicate at least one resource on whichpayload data are received;

Advantageously, the first control data indicates the resource on whichthe first control data are transmitted if payload data are to betransmitted in the second part.

The method for operating a receiving node may further comprise thesteps: Checking whether a resource on which the first control data arereceived is indicated by the first control data; Deciding whether thelater part contains second control data or payload data based on thecheck.

The invention does also relate to, a receiving node for a wirelesscommunication system comprising: a receiver for receiving a data framefrom a control node, wherein the data frame comprises an early part anda later part, wherein the early part comprises first control data forcontrolling the receiving node; a detector for detecting whether thelater part contains second control data or payload data; and a processorfor processing the later part in dependence of the detection.

The receiving node may further comprise: a checking entity for checkingwhether a resource on which the first control data are received isindicated by the first control data; a decision entity for decidingwhether the later part contains second control data or payload databased on the check.

Advantageously the receiving node is as relay node. The receiving nodemay also be a UE.

The invention is advantageously applied in LTE systems. In this respectit is pointed to the standards 3GPP LTE Rel-10 and to the technicalreports 3GPP TR 36.814 and 36.912.

An important aspect of the invention is to allow scheduling of data inthe resources unused for UL but only to the relay with DL assignment inthe preceding slot. Furthermore, the invention does not requirespecification of additional DCI formats as the interpretation of the DLassignments at the RN takes the presence/absence of an R-PDCCH in thesecond region for the same RN into account.

Further embodiments of the invention are further defined in thedependent claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a physical resource in a time frequency grid as used inLTE.

FIG. 2 shows a LTE time domain structure.

FIG. 3 shows an example of a scheduling decision indicating resourceblocks upon which the UE should receive data.

FIG. 4 shows an example of an eNB-to-RN transmission and a RN-to-UEtransmission on the basis of a frame structure.

FIG. 5 shows R-PDCCH multiplexing according to 3GPP RAN-1.

FIG. 6 shows a case having more DL assignments than UL grants.

FIG. 7 shows a radio communication system.

FIG. 8 shows a usage of second slot for an eNB-to-RN transmission.

FIG. 9 shows an example of proposed resource indication.

FIG. 10 shows a flowchart of a method for operating a control nodeaccording to one embodiment.

FIG. 11 shows a control node according to one embodiment.

FIG. 12 shows a flowchart of a method for operating a receiving nodeaccording to one embodiment.

FIG. 13 shows a receiving node according to one embodiment.

DETAILED DESCRIPTION

In many applications, it is desirable to time align (possibly within asmall offset) the subframe structure in the cells controlled by the eNBand cells controlled by the RN. As a consequence of this, the RN cannotreceive the normal control signaling from the RN at the beginning of asubframe as the RN need to transmit control signaling to the UE in thatpart of the subframe. Instead, L1/L2 control signaling from the eNB tothe RN need to be located later into the subframe.

Therefore, LTE-Advanced will support a new control channel, the R-PDCCH(Relay-Physical Downlink Control Channel), which is transmitted laterinto the subframe. An R-PDCCH carries, similarly to a PDCCH, either anuplink grant or a downlink assignment. Multiple R-PDCCHs (and possiblyother control channels defined for relay operation) can be transmittedand the time-frequency regions where these are transmitted are referredto as an “R-PDCCH region” herein. The R-PDCCH region will typically notoccupy the full system bandwidth during a subframe and the remainingresources can be used for transmission of data to UE and/or RNs.

Multiplexing the R-PDCCH with other transmissions in the downlinksubframe form the donor eNB can be done in different ways, e.g. pure FDMor FDM+TDM, each with their respective pros and cons.

These, options are discussed in U.S. 61/308,385, entitled R-PSCCHMultiplexing, which is herewith entirely incorporated into thisapplication.

Consider the option chosen by 3GPP as well. In 3GPP, the currentassumption is to divide subframes used for communication between RN endeNB into two parts (the boundary between the two parts could e.g.coincide with the slot boundary).

In the first part, located early in the subframe, R-PDCCHs containingtime-critical information, typically related to downlink transmission inthe same subframe, e.g. scheduling assignments, is transmitted. In thesecond part, located later in the subframe, R-PDCCHs containing lesstime-critical information, typically related to uplink activity in alater subframe, e.g. scheduling grants and, if defined, hybrid-ARQacknowledgements, is transmitted.

This is illustrated in FIG. 5. The system bandwidth is verticallydepicted, the time span of one subframe is horizontally depicted. Thesubframe is split at the slot boundary. A range in the verticaldirection defines a certain frequency band of the system bandwidth. Arange in the horizontal direction defines a certain time period in thesubframe. Control data for UEs, Data to relay nodes #k and #i, DLassignments for relay node #i, #j, #k, Uplink grants for relay nodes #x,#y, #z and data to UEs are transmitted on a specified frequency rangeand during a specified time span in the subframe as depicted in FIG. 5.For example, the DL assignment RN #i and the UL grant RN #x areRelay-Physical Downlink Control Channels.

Although in the FIG. 5 each R-PDCCH is illustrated to cover only onepart of the frequency band, it could equally well be distributed in thefrequency domain, e.g. to provide additional diversity. Note that uplinkrelated information may be transmitted in the first region as well ifnot all available resources in the region have been used for downlinkrelated information. The benefits of this structure is that downlinkassignments could be decoded early in the subframe, thereby reducing theoverall latency, while the somewhat less time critical uplink grants aretransmitted in the later part of the subframe.

The DL assignment and UL grant located in the same frequency region may(e.g. i=x in FIG. 5) or may not (i≠x) be related to the same RN. In casecell-specific reference signals are used for demodulation, both of theprevious cases are possible, while if UE-specific reference signals(also known as demodulation-specific reference signals) theassignment/grant should be directed to the same RN (i.e. i=x).

When the number of uplink grants transmitted from the eNB is less thanthe number of downlink assignments the question how to use the latterpart of the subframe in the resource blocks occupied by R-PDCCH arises.This situation is illustrated in FIG. 6. The latter parts of theR-PDCCHs which are not used for UL grants are marked by a “?”.

One possibility is to leave these resources unused. As long as the eachgrant/assignment consumes only a small amount of resources and/or thenumber of UL grants is not significantly smaller than the number of DLassignments, the loss in efficiency from this approach is acceptable.

Another possibility is to use these resources for transmission of datato relay nodes. However, this requires the definition of a new datachannel, the “R-PDSCH”, with a different (smaller) span in time than thealready existing PDSCH (the time span may also be different in differentresource blocks, depending on the scheduling decision). Furthermore,additional control signaling formats is required in order to scheduledata in the shortened “relay data region” (marked with “?” in FIG. 6) asthe current control signaling formats in LTE are defined assuming datatransmission over (more or less) the full subframe duration (i.e. boththe slots). This leads to additional specification and implementationcomplexity.

The first part of the invention is to allow using the resource blocksfollowing a DL assignment to RN #i for data to RN #i only (and not fordata to other RNs or UEs) as illustrated in FIG. 8. [The resource blockscould also be used for control signaling to the same or other RNs, butnot for data to other RNs.] In the following description it is assumedthat the first region (the DL assignment region) is located in the firstslot of a subframe and the second region (the UL grant region) islocated in the second slot of a subframe for simplicity but the methodcan easily be generalized to other splits between the first and secondregion.

FIG. 8 shows a structure of a subframe 1 (to be transmitted by an eNB)according to a time frequency grid. A duration 2 of the subframe 1amounts to 1 ms. The subframe 1 is divided in the time domain by a slotboundary 3 into a first slot 4 and a second slot 5. The first slot 4comprises a UE-control part 6 used for controlling UEs and a part 7,which can be used to transmit downlink assignments to relay nodes. Asystem bandwidth 8 is divided into several subbands. In a first subband9 during part 7 a DL assignment 14 for RN #i is transmitted and duringslot 5 (in subband 9) payload data 15 for the same RN #i aretransmitted. In a second subband 10 during part 7 and slot 5 payloaddata 16 to RN #i are transmitted. In a third subband 11 during part 7 aDL assignment 17 for RN #j is transmitted and during slot 2 (in subband11) payload data 18 for the same RN #j are transmitted. In a fourthsubband 11 during part 7 and slot 5, payload data 19 to UEs, e.g. aPhysical Downlink Shared Channel, are transmitted. In a fifth subband 13during part 7 and slot 5 payload data 20 to RN #j are transmitted.

It is important to note that the payload data 15 for RN #i, which is thesame relay node for which the DL assignment 14 has been transmitted, istransmitted on the same first subband 9. In other words, slot 5 onsubband 9 following the DL assignment 14 to RN #i is used for payloaddata to the same RN #i and not for payload data to any other relay node.Slot 5 on subband 9 may also be used for uplink grants to any RN. Thesame concept is also reflected on subband 11, where slot 5 is used forpayload data 18 to the same RN #j, for which the DL assignment 17 hasbeen transmitted during part 7 on the same subband.

The second part of the invention is to reuse the existing DCI formatsbut change the interpretation at the RN. The DCI formats for downlinkassignments used in LTE Rel-8 and later releases specify the resourcesupon which the receiver (UE) should expect data from the eNB to betransmitted. The resource indication specifies in the frequency domainwhich resource blocks to receive and it is implicitly assumed that thefull subframe (except the control region) is used for data transmission.Since a RN scheduled in the downlink knows upon which resources it hasreceived the DL assignment, it is proposed to, at the RN, exclude theresources occupied by the decoded R-PDCCH when determining upon whichresources the data from the eNB is to be received. This is exemplifiedin FIG. 9. Assume that the RN detects the downlink scheduling assignmenton the R-PDCCH transmitted on resource block 4 in the first slot andthat the scheduling assignment indicates data on resources 0, 1, 4 and6, e.g. using one of the DCI formats already specified for LTE Rel-8.The RN should in this case receive the corresponding data transmissionon resource blocks 0, 1 and 6 in the first slot and on 0, 1, 4 and 6 inthe second slot, i.e. resource block 4 (where the R-PDCCH was detected)is excluded from data reception in the first slot. For simplicityreasons the example assumed that the R-PDCCH ends at the boundarybetween the two slots of a subframe but the method can straightforwardlybe generalized to any split between the two “regions”. Similarly, toillustrate the principle in the invention, any guard time (e.g. unusedOFDM symbols at the beginning or the end of the eNB-RN transmissions)potentially required for the eNB-to-RN link is not part of theillustration but can easily be accounted for.

Obviously, the eNB should preferably hot transmit data to the RN onresources where the RN will not receive such data (resource block 4 inthe first slot in the example above). This can be achieved by modifyingthe R-PDSCH-to-RE mapping in LTE such that the REs in the first part ofthe subframe used by control signaling to the scheduled RN are skipped.From a transmitter perspective, the only difference would be a smallernumber of REs available to the PDSCH (due to some of them being used forcontrol signaling to the RN) while coding and modulation would remainthe same. Another possibility could be to separately encode the data forthe RB in the second slot (i.e. bits in RBs with frequency index 0, 1, 6in FIG. 9 are coded and modulated separately from bits in the RB withfrequency index 4, possibly with different modulation and codingschemes).

FIG. 9 shows one subframe 31 comprising a first slot 34 and a secondslot 35 separated by a slot boundary 33. In the frequency domain,resources are numbered from 0 to 9. Each number indicates a certainsubband. The slot 34 comprises a UE-control part 36 and a part 37, whichcan be used to transmit downlink assignments to relay nodes. In part 37,on subband 4 a downlink assignment 44 for RN #i is transmitted. In thisexample, the downlink assignment 44 indicates resource blocks 0, 1, 4and 6 for downlink transmissions to RN #i. The relay node RN #i learnsfrom this indication, that in part 37 of slot 34 and in slot 34 on thesubbands 0, 1, 6 downlink transmissions to RN #i can be received.Further, as the downlink assignment 44 has also indicated resource block4 and as the downlink assignment 44 has been received in part 37 onsubband 4, this situation will be interpreted that downlinktransmissions to RN #i are also received in the slot 35 on subband 4. Inthis way, slot 35 on subband 4 can also be efficiently used for downlinktransmissions to RN #i.

FIG. 10 shows a flowchart of a method for operating a control nodeaccording to one embodiment. The skilled person will note that themethod steps may at least partly be performed in different orders. Instep S1, the control node checks whether second control data (UL grant)are to be put into a later part. If second control data is not to be putinto the later part, payload data is scheduled into the later part instep S2. A data frame is created having an early part and the laterpart, wherein the early part comprises first control data (DLassignment) and the later part comprises payload data (step S3). Thecreated frame is transmitted.

With this, concept the later part can be used to transfer payload datain cases where second control data (UL grants) do not need to betransferred in the later part.

FIG. 11 shows a control node 50 according to one embodiment. The controlnode 50 comprises a controller 52 for creating a data frame having anearly part and a later part. From a scheduler 53 and a checking entity54, the controller learns, whether payload data or second control data(UL grants) is to be put into the later part. The early part comprisesfirst control data (DL assignments). The created data frame having anearly part and a later part is to be transmitted via a transmitter 51.

FIG. 12 shows a flowchart of a method for operating a receiving nodeaccording to one embodiment. In step S5, a data frame comprising anearly part and a later part is received from a control node, e.g.control node 50. In step S6, it is detected whether the later partcontains second control data (UL grant) or payload data. The furtherprocessing depends on the detection (step S7). The detection accordingto step S6 may be performed by the steps: checking whether a resource onwhich the first control data are received is indicated by the firstcontrol data by deciding based on the outcome of the check whether thelater part contains second control data or payload data. An indicationof the resource on which the first control data are received is e.g. theresource number 4 in FIG. 9. In this way a particular efficient methodfor detecting payload data in the second slot is obtained.

FIG. 13 shows a receiving node 60 comprising a receiver 61 for receivinga data frame from a control node, e.g. from control node 50. Thereceived data frame comprises an early part and a later part. The earlypart comprises first control data (DL assignments). Thedetector/controller 62 detects whether the second part contains secondcontrol data (UL grants) or payload data. For the detection thedetector/controller 62 may use a checking entity 63 for checking whethera resource on which the first control data are received is indicated bythe first control data and a decision entity 64 for deciding whether thelater part contains second control data or payload data based on anoutput of the checking entity 63.

ABBREVIATIONS

ARQ Automatic Repeat Request

CP Cyclic Prefix

DCI Downlink Control Information

DL Downlink

eNB eNodeB

eNodeB LTE base station

E-UTRAN evolved UMTS Terrestrial Radio Access Network

FDM Frequency Division Multiplexing

3GPP Third Generation Partnership Project

L1 Layer 1

L2 Layer 2

LTE Long Term Evolution

MBSFN Multicast Broadcast Single Frequency Network;

OFDM Orthogonal Frequency Division Multiplexing

PDCCH Physical Downlink Control Channel

PDSCH Physical Downlink Shared Channel

RB Resource Block

RE Resource Element

Rel Release

R-PDCCH Relay-Physical Downlink Control Channel

R-PDSCH Relay-Physical Downlink Shared Channel

TDM Time Division Multiplexing

UE User Equipment

UL Uplink

UMTS Universal Mobile Telecommunication System

The invention claimed is:
 1. A method for operating a control node for awireless communication system comprising the steps: creating a dataframe comprising a plurality of resource blocks, at least one of theplurality of resource blocks comprising an early part and a later part,wherein the early part of one of the resource blocks comprises firstcontrol data for controlling a relay node; checking whether secondcontrol data are to be put into the later part of the resource block onwhich the first control data are to be transmitted; scheduling payloaddata for the relay node into the later part of the resource block ifsecond control data are not to be put into the later part of theresource block; if the payload data are to be transmitted in the laterpart of the resource block, the first control data indicating theresource block on which the first control data are to be transmitted andthe first control data further indicating at least another one of theresource blocks on which payload data for the relay node are to betransmitted; and transmitting the data frame to the relay node.
 2. Themethod according to claim 1, wherein the first control data comprises adownlink assignment and/or the second control data comprise an uplinkgrant.
 3. The method according to claim 1, wherein the later parts aretransmitted with a higher throughput than the early parts.
 4. The methodaccording to claim 1, wherein each of at least some of the first partsand the second parts have a flexible border.
 5. The method according toclaim 1, wherein payload data for nodes other than the relay node arenot allowed to be transmitted on the resource block indicated by thefirst control data.
 6. A control node for a wireless communicationsystem comprising: a controller for creating a data frame comprising aplurality of resource blocks, at least one of the plurality of resourceblocks comprising an early part and a later part, wherein the early partof one of the resource blocks comprises first control data forcontrolling a relay node; a checking entity for checking whether secondcontrol data are to be put into the later part of the resource blockcomprising the first control data; a scheduler for scheduling payloaddata for the relay node into the later part if second control data arenot to be put into the later part; and a transmitter for transmittingthe data frame to the relay node, wherein the first control dataindicates the resource block on which the first control data are to betransmitted and indicates at least another one of the resource blocks onwhich payload data for the relay node are to be transmitted if thepayload data are to be transmitted in the later part.
 7. The controlnode according to claim 6, wherein the transmitter is adapted totransmit the later parts with a higher throughput than the early parts.8. The control node according to claim 6, wherein the control node is aeNodeB or a Pico-eNodeB.
 9. A method for operating a relay node for awireless communication system comprising the steps: receiving a dataframe from a control node, wherein the data frame comprises a pluralityof resource blocks, at least one of the plurality of resource blockscomprising an early part and a later part, wherein the early part of oneof the resource blocks comprises first control data for controlling therelay node; checking whether the resource block on which the firstcontrol data are received and at least another one of the resourceblocks on which payload data for the relay node are received areindicated by the first control data; determining that the later part ofthe resource block contains payload data if the resource block isindicated; and processing the later part according to the determination.10. A relay node for a wireless communication system comprising: areceiver for receiving a data frame from a control node, wherein thedata frame comprises a plurality of resource blocks, at least one of theplurality of resource blocks comprising an early part and a later part,wherein the early part of one of the resource blocks comprises firstcontrol data for controlling the relay node; a checking entity forchecking whether the resource block on which the first control data arereceived and at least another one of the resource blocks on whichpayload data for the relay node are received are indicated by the firstcontrol data; a decision entity for determining that the later part ofthe resource block contains payload data if the resource block isindicated; and a processor for processing the later part according tothe determination.
 11. The relay node of claim 10, wherein the decisionentity excludes an early part of the indicated resource block as acarrier of payload data when determining that the later part containsthe payload data without an explicit instruction in the data frame toexclude the early part.